Apparatus for photoelectric sensing of knitted fabrics



Feb. 24, 1970 o, MQTIN ET AL 3,496,739

APPARATUS FOR PHOTOELECTRIC SENSING OF KNITTED FABRICS Filed April 25, 1968 3 Sheets-$heet 1 Am- 6W %0TW AN mamas Emma. JJVENTORS Feb. 24-, 1970 o, MOTlN ET AL 3,496,739

APPARATUS FOR PHOTOELECTRIC SENSING OF KNITTED FABRICS Filed April 25, 1968 3'Sheets-Sheet 2 awv mom m, mamas EEMNHEL mm,

INVENTORS Feb. 24, 1970 MOTIN ET AL 3,496,739

APPARATUS FOR PHOTOELECTRIC SENSING OF KNITTED FABRICS Filed April 25, 1968 3 Sheets-Sheet 5 FiqfQ MMW Ash EMWES EfiANUEL LlNbN INVENTQRS United States Patent O 3,496,739 APPARATUS FOR PHOTOELECTRIC SENSING F KNITTED FABRICS Karl Olov Motin, Halmstad, and Johannes Emanuel Lindn, Sjomarken, Sweden, assignors to Motin 8; Co. Aktiebolag, Halmstad, Sweden, a corporation of Sweden Filed Apr. 25, 1968, Ser. No. 724,115 Claims priority, application Sweden, May 11, 1967, 6,589/ 67 Int. Cl. D04b 35/18 US. Cl. 66-163 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an apparatus for photoelectric sensing of knitted fabrics at their manufacture in circular knitting machines for detecting errors in the knitted fabric. The object of the invention is to provide an apparatus by which the errors are detected immediately after their occurrence so that they can be corrected with a minimum of waste of fabric. This object and others have been achieved by providing the apparatus with a light source sending light rays towards photoelectric cells situated in such a way that the rays emitted from the light source are reflected towards the peripheral surface borders of the two needle beds of the knitting machine near one of the knitting places before they hit the photoelectric cells.

At the manufacture of fabrics such as locknit charmeuse and similar knitted fabrics in circular knitting machines it is very important that the fabric which is continuously manufactured in the machine be sensed continuously such that at the occurrence of errors of different kinds in the same, e.g. at a failure of loops at a needle break etc. the machine is stopped as soon as possible for removing the error since the longer the error remains the greater a part of the fabric has to be wasted. For this reason error sensing apparatuses have been constructed which comprise a photoelectric cell (a photoelectric element) which is influenced by reflected rays from the fabric in the machine. When e.g. a loop error occurs, the machine driving force is interrupted due to the impulse occurring in the photoelectric cell caused by the changed value of the light reflection via an amplifier and a relay, and the machine is stopped. At the manufacture of thick fabrics it has, however, turned out that the loop failure on the rear side of the fabric cannot be sensed by the sensing apparatus. This means that long parts of the manufactured fabric have to be wasted.

The object of the present invention is to overcome these drawbacks. The invention relates more particularly to a photoelectric sensing apparatus for circular knitting machines of the kind provided with a needle cylinder having vertically operating needles and a so called dial with horizontally operating needles, said apparatus comprising two photoelectric cells illuminated by a light source, said cells adapted to transmit electric impulse to a device for discoupling the source of driving force of the machine,

The main feature of the invention is to be seen therein that the light source and the photoelectric cells are situated in such a way that the rays emitted from the light source are reflected towards the peripheral border surfaces of the needle beds in the vicinity of one of the knitting places before the rays hit the photoelectric cells. By means of such a device all the loops will be sensed at the place where they are formed. Also in thick fabrics the loops will be available for sensing for the reason that they are open at the knitting place and thus, it will be possible to detect errors at the place for the loop formation. Further, the sensing will be independent of the coulor of the yarn and one can easily work with yarns of different colours.

According to a preferred embodiment of the invention the two photoelectric cells as well as the light source are carried by a holding arm being adjustable in relation to a bracket adapted to be arranged preferably on the stand of the knitting machine. It is hereby rendered possible to adjust the light source and the photoelectric cells at an angle with the actual peripheral edge borders of the needle bed in front of which the formed loops extend in such a way that there is obtained the best possible light reflection effect and thus also the best possible sensing result.

In the following the invention will be elucidated with reference to the accompanying drawings. In the drawings:

FIG. 1 shows a vertical section through a part of the needle cylinder of a circular knitting machine and dial provided with a sensing apparatus according to the invention,

FIG. 2 is a side elevation of the sensing apparatus proper,

FIG. 3 shows the same apparatus from the outside of the machine,

FIG. 4 shows diagrammatically a knitting place on the machine,

FIG. 5 shows a correct loop picture,

FIG. 6 shows a loop failure in the back of the knitted fabric,

FIG. 7 shows a loop failure on the front side of the fabric,

FIG. 8 shows diagrammatically the ray path at the sensing,

FIG. 9 shows an electric block diagram,

FIG. 10 shows a transistor amplifier included in the diagram, and

FIG. 11 shows a tube amplifier.

Referring now to FIG. 1, the needle cylinder of the knitting machine has been denoted with 1, it dial with 2 and the annular interstice between these two parts through which the knitted fabric 3 is fed in downward direction has been denoted by reference numeral 4. The needles 5 of the cylinder 1 operate vertically in a needle bed 6 and the needles 7 of the dial 2 operate horizontally in a needle bed 8.

There is on the machine stand 9, by means of screws 10, attached a bracket 11 to the upper portion of which there is by means of a clamping bolt 12 attached one end of a holding arm 13 in such a way that it can be brought to assume different inclining positions. At the opposite end of the holding arm 13 there is by means of a clamping bolt 14 attached a sleeve 15 for a lamp 16 connected to a source of electric power, said lamp directing bundles of rays 17, 18 towards strictly defined surfaces 19 and 20 on the peripheral edge surfaces 21 and 22, forming an angle of with one another, of the cylinder 1 and the dial 2. On either side of the holding sleeve 15 there are by means of bolts 23, 24, attached holding sleeves 25 and 26 for each their photoelectric cells 27, 28. The holding sleeves 15, 25 and 26 are adjustable in such a way that they can enclose any desired angle with the feeding direction of the needle cylinder 1.

The whole of the sensing apparatus is aggregated to form an easily mounted unit, on the knitting machine. It is coupled via a cable, provided with contacts, to a conventional amplifier 29 (FIG. 9) of a transistor or tube type (FIGS. 10 and 11). The amplifier is via a Schmitt trigger 30, a flip-flop-coupling 31 and a second amplifier 32 connected to a relay 33 for switching off the drive motor 34 of the knitting machine and for giving a signal to an indication signal 35. A voltage stabilizator con nected to the electric network has been denoted by reference numeral 36 in the block diagram 9.

When the ray bundles 17, 18 are reflected against the polished surfaces 21, 22 at the places denoted by reference numerals 19 and 20 in FIG. 8 and then hit the photoelectric cells 27 and 28 a current impulse is created which accordng to FIG. 10 enters on the 'base 37 into a transistor 38 such that the output to the Schmitt trigger 30 is reduced. The same thing is true when according to to FIG. 11 the current impulses flow through, the photoelectric cell 27 or the photoelectric cell 28 which enter on the grid 39 to a triod as also in this case the output to the Schmitt trigger 30 is reduced. In both cases the current impulses through the photoelectric cells 27, 28 causes a discoupling of the source of driving force and the machine stops.

This effect is utilized for sensing the loops at the knitting place according to FIGS. 47. If namely the loop picture as shown in FIG. is correct, no increased current impulses occur through the photoelectric cells 27, 28 for the reason that the ray bundles 17, 18 from the lamp 16 are reflected evenly against the surfaces 19, 20 (FIG. 8) on the needle cylinder 1 and the dial 2 behind the loops 41, 42 formed. However, in case the needle 7 in the dial 2 as shown in FIG. 6 is damaged or broken and thus unable to catch its loop 41, the surface 20 is uncovered. This means that the photoelectric cell 28 will be illuminated more intensively and thus give a current impulse to the transistor 38 and the tube 40, respectively, which as described above causes the driving motor 34 to be switched off and the knitting machine to be stopped.

In case according to FIG. 7 the needle 5' is defective or broken, the course of events will be the same. The needle 5' may then not retain the loop 42. The surface 19 of the cylinder 1 in front of the needle 5 will be completely uncovered. This causes the photoelectric cell 27 to be illuminated more intensively and thus give an impulse to the transistor 38 or the tube 40, respectively. Also in this case the machine is stopped and at the same time the indication device gives an optic or acoustic signal which calls the attention of the operator.

Thus, the machine will obviously be automatically brought to stop as soon as a loop error occurs in the material. The error may immediately be corrected and the machine then be restarted.

The invention has been described in the aforegoing for purposes'of illustration only and is not intended to be restricted by this description or otherwise except as defined in the appended claims. Thus, the different part of the sensing apparatus may be constructively modified in many ways without departure from the inventive idea. This is true in particular of the device for the suspension of the light source 16 and the photoelectric cells 27, 28 and the adjustment for these means in such a way that correct angles of entry and reflection of the ray bundles 17, 18 are obtained.

In order to make the description complete it should also be mentioned that there is obtained by means of the invention a further advantage to be explained here below.

It is sometimes desired to make a strip in the knitted material along which the material is cut after the treatment. Also, the patterns are sometimes made with only one or several needles 5, 7 in the needle cylinder. So as to prevent the machine from stopping at such loop failures one either has to cover the surfaces 19, 20 at the place or places in question of the needle cylinder or a micro switch has to be applied which interrupts the impulse from the photoelectric cells 27, 28 when in said case there is obtained an undesired reflection from the surfaces 19, 20. By means of the present invention a much smipler solution is obtained by using needles 5, 7 with a dark coating plate covering the areas 19, 20 respectively, and thus prevent a reflection from these areas when a marking strip or a special pattern knitting is desired in the knitted material.

What we claim is:

1. An apparatus for photo-electric sensing of whether the needles have taken a yarn in their hooks during the manufacture of knitted fabrics in circular knitting machines of the kind provided with a needle cylinder (.1) having vertically operating needles (5) and a so called dial (2) having horizontally operating needles (7), said apparatus comprising two photoelectric cells (27, 28) illuminated by means of a light source (16), said cells adapted to transmit, via an amplifier (29), electric impulses to a device for discoupling the driving source (34) of the machine, wherein the improvement comprises arranging the light source (16) and the photoelectric cells (27 28) so that the rays emitted from the light source are reflected towards the peripheral border surfaces (21, 22) of the two needle beds (6, 8) close to one of the knitting needles before the rays hit the photoelectric cells (27, 28).

2. An apparatus as claimed in claim 1, wherein the improvement comprises a holding arm (13) for the two photoelectric cells (27, 28) as well as for the light source (16), said holding arm (13) being adjustable in relation to a bracket (11) preferably arranged on the stand (9) of the knitting machine.

3. An apparatus as claimed in claim 2, wherein the improvement comprises making the photoelectric cells (27, 28) and the light source (16) swingably adjustable in relation to the holding arm (13).

References Cited UNITED STATES PATENTS 1,980,294 11/1934 Ross et al.

2,438,365 3/1948 Hepp et a1.

2,522,101 9/1950 Dion et al.

3,132,254 5/1964 Woodward 66163 XR 3,397,317 8/1968 Dosch 250219 3,421,007 1/1969 Schwartz 250-219 XR RONALD FELDBAUM, Primary Examiner US. Cl. X.R. 

